1. Field of the Invention
The present invention relates to a vehicle environment monitoring apparatus which monitors the environment of the vehicle on the basis of the images taken by the imaging unit mounted on the vehicle.
2. Description of the Related Art
Conventionally, there is known a configuration of detecting an object existing in the surroundings of a vehicle by a so-called stereo camera in which two cameras are mounted with their optical axes parallel to each other, and calculating a distance between the object and the vehicle using a disparity, by calculating the disparity from the image area within the image from the right camera and the image area within the image from the left camera with respect to the identical object. And there is proposed a vehicle environment monitoring apparatus which determines the possibility of contact between the object and the vehicle, on the basis of the distance between the object and the vehicle calculated using the disparity (for example, refer to Japanese Patent Laid-Open No. 2001-6069).
When detecting the object existing in the range up to a long range, for example exceeding 100 m, from short range in the vicinity of the vehicle by the algorithm disclosed in Japanese Patent Laid-Open No. 2001-6069, the influence of the variation in the optical axes of the two cameras increase for detecting the object existing at a long range, so that the error in the calculated distance becomes large. Therefore, it was difficult to determine stably the possibility of contact between the object and the vehicle for all the range from short range to long range.